Machines for bending pipes, rods and bars



Nov. 15, 1966 s. v. ESKILSON MACHINES FOR BENDING PIPES, RODS AND BARS 2 Sheets-Sheet 1 Filed Dec. 16. 1963 FIGJ Nov. 15, 1966 s. v. ESKILSON MACHINES FOR BENDING PIPES, RODS AND BARS 2 Sheets-Sheet 2 Filed Dec United States Patent 3,285,048 MACHINES FOR BENDING PIPES, RODS AND BARS Sture Viking Eskilson, Hassleholm, Sweden, assignor to Backer Elektro-Viirme Aktiebolag, Sosdala, Sweden, a corporation of Sweden Filed Dec. 16, 1963, Ser. No. 330,921 Claims priority, applicsatao/rlgweden, Jan. 18, 1963, 3 Claims. (Cl. 72-150) This invention relates to a machine for bending pipes, rods and bars.

In many fields of technics, for instance the machine shop and building industries, pipe and rod lengths require bending at definite points and at definite angles. For realizing such bending there have hitherto been available but simple, manually operated machines which comprise for instance a stationary bending table with an ups-tanding bending mandrel about which a pipe or rod length, clamped between jaws in the vicinity of the mandrel, is bent by means of a pivotally mounted bending lever engaging the pipe or rod length at a suitable point on the side of the mandrel opposite to the clamping jaws. In connection with large series, however, the operation of such a simple machine proves physically tiring to the operator and is also time-consuming. Moreover, the friction between the work piece and the part of the lever engaging it can produce tensile stresses in the work piece which may result in ruptures.

The invention has for its object to provide a novel type of bending machine in which pipes, rods and bars can be bent with lesser physical efforts and at higher working speeds than hitherto. The machine is characterized by the fact that it comprises a rotatably mounted, preferably motor-driven bending head which on its end surface carries a mandrel coaxial with the axis of rotation of the head, and a dog which is laterally offset in relation to the mandrel and serves to take along a pipe or rod length placed between the mandrel and the dog, and that a sector-shaped abutment for the pipe or rod length is pivotally mounted on a shaft parallel to the axis of the bending head and fixedly arranged in relation to the machine frame at a radial distance from the axis of the bending head larger than that of the dog from said axis, said radial distance being so adapted relative to the radius of the sector-shaped abutment that the sector edge surface thereof constitutes a direct extension of the surface of application of the dog for the pipe or rod length in the position occupied by the bending 'head at the start of a bending operation in order that the abutment may be carried along by the pipe or rod length at the application of said length against said abutment during the bending operation.

These and further feature of the machine and the advantages thereof will appear from the following description in which reference is made to the accompanying drawings in which:

FIG. 1 is an elevational view of the machine, partly in vertical section;

FIG. 2 is a plan view of the machine;

FIG. 3 is an elevational view of a detail.

The machine illustrated in the drawings has a frame 1 with a sheet metal covering 2 and a door 3- at the front. At its upper end the frame supports a bottom plate 4 which in turn supports a clutch head 5 mounted for rotation on said bottom plate, a bending head 7 secured to the upper side of said bottom plate by means of bolts 6, a stationary machine insert comprising an intermediate bearing plate 8 and a metal sheet 9 mounted on top of said plate 8. The intermediate bearing plate .and the metal sheet 9 are suspended by means of bolts 10 at some 3,285,048 Patented Nov. 15, 1966" 'ice distance beneath the bottom plate 4. Suspended by means of bolts 11 from the bearing plate 8 are a pneumatic device 12 and an upwardly directed universal joint shaft 13 which is connected to said pneumatic device 12 and the upper edge of which is mounted in the clutch head. Secured on the shaft 13 is a gear 14 which is in engagement with a driving gear 15 (indicated in FIG. 2) on the output shaft of a reduction gear (not shown) over which power is supplied from an electric motor. On the upper side of the gear 14 is disposed a clutch cone 17 which is fixedly united with the gear 14 by bolts 16 and adapted to cooperate with the clutch head 5 when said cone is raised to an upper position by means of the pneumatic device 12 to transmit power to the bending head 7. The device is electro-magnetically controlled by means of a circuit which is adapted to be closed manually and opens automatically as will be explained in the following.

On the upper side the bending head 7 has an exchangeable bending mandrel 18 which is screwed into a threaded hole in center of the bending head and which determines the radius of curvature of the bending to be performed on a pipe or rod length. Also provided in the bending head is a downwardly widening, i.e., keyhole-shaped guide groove 19 which extends rectilinearly from the circumference of the head in a parallelly laterally offset relationship to a diameter of said head and serves to secure a movable dog 20 in the desired position in said groove by means of a tensioning screw 21. As shown in FIG. 3, the dog 20 has an upstanding shoulder 22 against which the pipe or rod 23 to be bent is applied in that the dog 20 i clamped in such a position in the groove 19 that the distance between the mandrel 18 and the shoulder 22 (measured at right angles to the latter) is equal to the diameter of the pipe or rod.

Provided in the circumference of the bending head 7 is a eross-sectioually dovetailed groove 24 in which a stop mean-s 25 of corresponding shape is 'slidable and can be clamped in the desired position by means of a tensioning' screw (not shown). The bending head 7 has a position of rest which is determined by a stop means (not shown) fixedly mounted on its circumference abutting a stop means (not shown) on the bottom plate 4. Upon operation of the bending head 7 after engagement of the clutch 5, 17 by means of the pneumatic device 12, whenthe latter has been made operative by manual closing of the the abovementioned circuit, the head 7 turns against the action of a return spring (not shown) until the stop means 25 meets a switch means (not shown) disposed in the path of said stop means and serving to automatically open the circuit so that the head stops and is then returned to its position of rest in which said switch means is again closed by suitable means. The angle of rotation of the bending head 7 is determined by the position of the stop means 25. The angular range within which the stop means can be set amounts to approximately A sector-shaped arm 26 serving as an abutment for the pipe or rod 23 is pivotally mounted at one end in the center of the sector on the vertical pivot pin 27 which is fixedly arranged in relation to the bottom plate 4 at one side of the machine frame but can be set in positions at various distances from said bottom plate. For this purpose, the bottom plate 4 has a lateral projection 28 welded to it, and a threaded lower endportion of the pivot pin 27 is inserted in a slot 29 in said later-a1 projection 28 and clamped in the desired position along said slot by means of a nut 31. The position of rest of the bending heading 7 is chosen in such a way relative to the lateral projection 28 that in this position the guide groove 19 is parallel with, but slightly laterally off-set from, the slot 29. The arm 26 has a position of rest (determined as explained in the following) in which one side edge of the arm is aligned with one end edge of the dog 20, as shown in FIG. 2. By choosing a correct position for the pivot pin 27 in the slot 29 the sector edge surface of the arm 26 is caused to form an-extension of the inner side edge surface of the dog 20. On the upper side adjacent to the sector edge the arm 26 has an elevated portion 32 which extends concentrically with said sect-or edge and has a surface of application for the pipe or rod 23, said surface forming a direct extension of the surface of application on the shoulder 22.

At a point at the underside of the arm 26 the end of a cable 33 is fixed, and said cable is passed over a pulley 34 (mounted at the rear on top of the machine frame 1) down into the frame where it carries a weight 35 for returning the arm 26 to the FIG. 2 position after the arm has been carried along clockwise as seen in FIG. 2 during a bending operation. The bending of a pipe or rod length 23 is performed as follows. The dog 20 is first set at that distance from the mandrel which corresponds to the pipe or rod diameter, and then the pipe or rod is placed freely between the mandrel 18 and said dog 20 in such a position that one end of said pipe or rod, preferably that which is the lowermost one in FIG. 2, will bear against an abutment Which is not shown in the drawings but may be adjustably'mounted on the bending head 7 or the bottom plate 4 or on some support altogether outside the bending machine to determine at what distance from the end the bending shall begin. The machine is started, and during the rotation of the bending head 7 the dog 20- bends the pipe or rod around the mandrel 18 while the arm 26 ofiers the necessary support for the bending operation. As the bending proceeds the pipe or rod is pulled forwards, taking the arm 26 along which swings clockwise, lifting the weight 35. When the stop means 25 abuts the earlier mentioned switch, the bending head will stop and immediately return to position of rest while the arm 26 is pulled back by the weight 35. The best pipe or rod remains lying loosely about the mandrel and can be removed by hand.

The machine as described above can be utilized for bending not only pipes and rods of the same material throughout but also pipes the hollow interior of which is entirely filled with another material. The machine is particularly suited for bending electric tubular heating elements having an outer tubular sheath in which one or more resistance wires are embedded in a tightly compasted mass of pulver'u-lent insulating material.

What I claim and desire to secure by Letters Patent is:

1. A machine for bending a pipe, rod and bar, coanprising a rotatably mountedrnotor-driven bending head.

having on its end surface an exchangeable mandrel coaxial with t-he axis of rotation of the head, a dog which can be rfixed at difierent'distances from the mandrel and serves to take along a length of the pipe or rod placed between the mandrel and the dog, a sector-shaped abutment for the length of the pipe or rod, a machine frame with said abutment being pivotally mounted on a shaft parallel to the axis of the bending 'head and fixedly arranged in relation to said machine frame at a radial distance from the axis of the bending head larger than that of the dog from said axis, said radial-distance being so adapted relative to the radius of the sector-shaped abutment that the sector edge surface thereof constitutes a direct extension of the surface of application of the dog for the length of pipe or rod in the position occupied by said bending head at the start of the bending operation in order that said abutment may be carried along by the length of pipe or rod at the application of said length against said abutment during the bending operation and said distance being adg'ustable to permit retaining the lateral edge surface of said abutment as an extension of the surface of application of said dog at various distances of said dog from said mandrel, and stop means in said head for limiting the turning angle of said head from a rest position to realize bending angles of desired size in the length of pipe, rod or bar.

2. A machine according to claim 1, wherein said stop means comprises a first stop member being displaceable in a groove in a circumference of said bending head and a second stop means which is disposed on said bending head for determining the position of rest thereof.

3. A machine according to claim 2, wherein said first stop means is adapted to actuate a means controlling the motor drive of the bending head to stop the latter when it has turned through the angle corresponding to the position of the stop means.

References Cited by the Examiner UNITED STATES PATENTS 983,664 2/1911 Wilson 72-159 2,621,702 12/ 196 2 Peddinghaus et al. 72149 CHARLES W. LANHAM, Primary Examiner. R. D. GREFE, Assistant Examiner. 

1. A MACHINE FOR BENDING A PIPE, ROD AND BAR, COMPRISING A ROTATABLY MOUTED MOTOR-DRIVEN BENDING HEAD HAVING ON ITS END SURFACE AN EXCHANGEABLE MANDREL COAXIAL WITH THE AXIS OF ROTATION OF THE HEAD, A DOG WHICH CAN BE FIXED AT DIFFERENT DISTANCES FROM THE MANDREL AND SERVES TO TAKE ALONG A LENGTH OF THE PIPE OR ROD PLACED BETWEEN THE MANDREL AND THE DOG, A SECTOR-SHAPED ABUTMENT FOR THE LENGTH OF THE PIPE OR ROD, A MACHINE FRAME WITH SAID ABUTMENT BEING PIVOTALLY MOUNTED ON A SHAFT PARALLEL TO THE AXIS OF THE BENDING HEAD AND FIXEDLY ARRANGED IN RELATION TO SAID MACHINE FRAME AT A RADIAL DISTANCE FROM THE AXIS OF THE BENDING HEAD LARGER THAN THAT OF THE DOG FROM SAID AXIS, SAID RADIAL DISTANCE BEING SO ADAPTED RELATIVE TO THE RADIUS OF THE SECTOR-SHAPED ABUTMENT THAT THE SECTOR EDGE SURFACE THEREOF CONSTITUTES A DIRECT EXTENSION OF THE SURFACE OF APPLICATION OF THE DOG FOR THE LENGTH OF PIPE OR ROD IN THE POSITION OCCUPIED BY SAID BENDING HEAD AT THE START OF THE BENDING OPERATION IN ORDER THAT SAID ABUTMENT MAY BE CARRIED ALONG BY THE LENGTH OF PIPE OR ROD AT THE APPLICATION OF SAID LENGTH AGAINST SAID ABUTMENT DURING THE BENDING OPERATION AND SAID DISTANCE BEING ADJUSTABLE TO PERMIT RETAINING THE LATERAL EDGE SURFACE OF SAID ABUTMENT AS AN EXTENSION OF THE SURFACE OF APPLICATION OF SAID DOG AT VARIOUS DISTANCES OF SAID DOG FROM SAID MANDREL, AND STOP MEANS IN SAID HEAD FOR LIMITING THE TURNING ANGLE OF SAID HEAD FROM A REST POSITION TO REALIZE BENDING ANGLES OF DESIRED SIZE IN THE LENGTH OF PIPE, ROD OR BAR. 